


my heart is filled with your fingerprints

by SunSparrow



Category: NCT (Band)
Genre: Alternate Universe - Supernatural Elements, Enthusiastic Consent, Fluff and Smut, Halloween, House Party, M/M, Mating Cycles/In Heat, Monster Boyfriends, Multiple Orgasms, Oppa Kink, Plot What Plot/Porn Without Plot, Protective Nakamoto Yuta, References to Knotting, References to alpha/beta/omega dynamics, Tentacles, brief mention of breeding, monsterfuckers unite, octomerman!Yuta, werewolf!mark
Language: English
Status: Completed
Published: 2020-11-01
Updated: 2020-11-01
Packaged: 2021-03-08 17:41:43
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 2,998
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/27180559
Author URL: https://archiveofourown.org/users/SunSparrow/pseuds/SunSparrow
Summary: Mark is the unluckiest werewolfever.So maybe that's an exaggeration, but he's just realized that his heat has overlappedperfectlywith the Halloween party his friends have planned for tonight. He's just glad there's no full moon.Mark eyes the waxing gibbous outside the window suspiciously.
Relationships: Mark Lee/Nakamoto Yuta
Comments: 16
Kudos: 289
Collections: Challenge #2 — tricks; treats; and terrors





	my heart is filled with your fingerprints

**Author's Note:**

> Title from Taemin's "Criminal."

Mark is the unluckiest werewolf _ever._

So maybe that's an exaggeration, but he's just realized that his heat has overlapped _perfectly_ with the Halloween party his friends have planned for tonight. He's just glad there's no full moon.

Mark eyes the waxing gibbous outside the window suspiciously.

He was naively hoping his heat cycle wouldn't come early since he was so set on wearing his Ash Ketchum costume. But he should have paid attention to the clear signs—the inexplicable hoard of blankets in his room, the all-over body ache, the desire to cuddle his best friends to kingdom come—and now it's one hour into the party and he's broken into a feverish sweat. Denial isn't just a river in Egypt, and Mark's obstinate refusal to miss Johnny's legendary end-of-the-year bash is going to be his downfall.

With a whine, Mark topples over on a random couch to wither and pass out from misery.

"Hi, Mark," a familiar voice says fondly.

Mark stares up at the newcomer from his position on the couch, both legs splayed over the sofa arm.

Yuta's beautiful, as all merfolk of his kind are. His lavender hair has a glowy shine, perpetually wet. Tonight, little pieces of glitter and starry sequins dust his cheeks and around his eyes. He's shirtless under the silver-studded white jacket he wears, with jeans so tight they're practically painted on, like some glam rock star.

Mesmerized, Mark doesn't notice when Yuta leans in close. "You seem jittery tonight." The warm puffs of air against Mark's ear make him involuntarily shudder and inhale sharply, his senses ridiculously heightened by his heat.

At the sound of Mark's breathy little gasp, Yuta _recoils,_ his eyes dilating as he stares Mark down for far too long. Mark thinks dazedly that Yuta should get on top of him and do something about this _fire_ that's smoldering beneath his skin—

"Mark. You're shivering _and_ sweating. Are you sick?" Yuta's brow is furrowed with concern.

Mark shakes his head, feeling dizzy.

Yuta's eyes narrow. He snarls, "Did someone _drug_ you?"

"N-no!" Mark denies quickly, struggling to sit up, the words clumsy on his tongue. The last thing he wants is for Yuta to interrogate and strike down some innocent soul. "Just—" Mark trembles, standing on uncertain feet.

Yuta's body suddenly looks so welcoming and cool in all pastel hues. Perfect for cuddling.

"Yuta-hyung," Mark finds himself choking out, flinging himself into Yuta's arms. To his relief, Yuta immediately clasps his arms around Mark, pulling him close, and Mark instantly feels refreshed as he inhales Yuta's clean, cool scent.

Before, Mark and Yuta went on a couple of dates, but... nothing really happened. They hung out like any friends would, going to the diner for a burger and fries, or Netflix-and-chilling, sans any sexy connotations. It wasn't _dating,_ per se. Mark was always too nervous to kiss Yuta, and after the second date, Mark didn't ask Yuta out again.

To be fair, Yuta never asked either.

Mark isn't even sure if Yuta even likes him that much.

The thought makes his eyes inexplicably tear up and a lump form in his throat. "Yuta-oppa," he pleads, falling back on their old joke, _except it isn't really a joke this time._ "Do you like me?"

Something in Yuta's expression wavers under Mark's fixed gaze. "Of course, Markie. You're my favorite, you know that." He nuzzles Mark's hair so gently that it makes Mark _ache._

"Then why aren't you my boyfriend?" Mark asks, even though he shouldn't, because the answer is going to break his heart. And as hormonal and needy as he is, he's going to cry, and there's going to be snot involved, and it's going to be very, very uncool.

"You want me to be your boyfriend?" Yuta asks after a pause, ever so gently. He hooks his finger under Mark's chin to tilt his face upwards.

"Yes," Mark sniffles, briefly acquiescing to Yuta's little attempt to keep him open and transparent. Then he ducks his head into Yuta's neck.

"Okay, baby." The tenderness in Yuta's voice plucks at Mark's heartstrings. He strokes Mark's hair, Mark arching up into his touch like a cat stretching in a ray of sunshine. "I'll be your boyfriend."

Joy bubbles up in Mark's chest. "Okay," he says happily, nuzzling into the curve of Yuta's neck. He finds himself tangling his fingers with Yuta's, pulling and tugging until they're heading upstairs. Where Mark knows there are plenty of guest bedrooms. Maybe Mark's heat is to blame—but maybe it's just his overwhelming depth of _feeling_ for Yuta, and the want that has been simmering under the surface all this time. 

"Where are you taking us, baby?" Yuta asks, tone still soft.

"Upstairs," Mark insists, before crowding Yuta up against the bar of the stairwell and kissing along his neck, the beautiful line of his jaw. He scrapes his sharp canines lightly against the side of Yuta's throat, wanting to bite, to _own,_ the animalistic possessiveness in him flaring higher.

"Baby," Yuta says, hesitating, his hands on Mark's shoulders. Yuta's not pushing him away but Mark senses the reluctance before Yuta says anything else, and it feels like rejection. Mark whimpers, pushing himself against Yuta more insistently, knocking Yuta into the banister. "Mark, don't get me wrong, I'd love to take you to bed, but isn't this too fast for you?"

_For you._

Mark answers first by straddling Yuta's thigh and riding it, his dick so, so hard. "Not too fast," Mark breathes, nipping at Yuta's bottom lip. "I'm going into heat, hyung. Want you to spend it with me."

"Heat?" Yuta clutches at Mark's hips, helping him thrust and grind. "I've never spent a heat with someone, baby, I don't know what to do." He looks so worried as he touches Mark like he's made of glass—now that won't do at all.

"Me. You do me," Mark giggles. He slides his hand firmly down the flat planes of Yuta's chest, his abs, down, down to cup the front of his pants to gauge Yuta's interest.

And Yuta is _definitely_ interested. Mark smirks, flashing sharp canines.

 _"Fuck,_ Mark. Okay," Yuta groans, grabbing Mark's wrist and _pushing_ the heel of Mark's hand into his clothed dick as he tugs Mark by the waist harder onto his thigh. Mark's vision goes white-hot for a second as he imagines himself coming all over Yuta's thigh, right in the middle of the party, and he _moans._

Panting, Mark hooks his finger through Yuta's belt loop. "We'll figure it out," Mark promises, more for Yuta's sake than his own.

It's a blur of needy kisses and discarded clothes as Mark tugs Yuta into one of the empty bedrooms, begging, "Come on, hyung, I need you." Slick is trailing down Mark's leg; the seat of his boxers is soaked. Any alpha wolf would be drunk off the scent already, but Yuta is coherent, all there, able to take care of Mark the way only Yuta can.

Somehow they make their way onto the bed, Yuta finally on top of Mark like the best kind of blanket.

"I don't know if I can even help, Mark. I'm not a were," Yuta murmurs, even as he's kissing up and down Mark's neck, biting at the sensitive skin. "Are there like, pheromones involved?" he asks helplessly.

"Nope, just need you in me, like, yesterday," Mark says, panting hard. He takes Yuta's hand and unceremoniously shoves it down the back of his boxers so Yuta can understand.

"Oh my g—" Yuta chokes on air, "You're so _wet."_

Mark can't help but giggle at the awe on Yuta's face. "Yeah, one of the perks of heat." He tugs Yuta down to crash their lips together. "Now _fuck_ me." Mark can't stop trying to rut up against Yuta—feverish, feral. Yuta plants one knee between Mark's spread legs, and just the pressure of Yuta's muscled thigh against Mark's cock through thin boxers makes Mark see _stars._ He whimpers, humps Yuta's thigh and chases his first orgasm—wants to hurl himself off that cliff to take off some of the edge. Yuta helps, kissing Mark with syrupy insistence; Mark keens into Yuta's mouth as he comes, his whole body tingling with pleasurable aftershocks.

Mark's boxers are soaked, but he's still so hard it _hurts._

"Need," Mark begs. His empty hole is oozing even more copious amounts of slick. "Need you in me, I'm wet, I'm _gushing."_

"The fucking _mouth_ on you, Mark," Yuta groans, ripping Mark's boxers off and grabbing his cock; it's soaked in semen, and Mark gasps as Yuta pumps him with sure, steady strokes. "Gonna fuck you so good," Yuta grits out, "I'll make you feel so good, baby." Yuta presses Mark's knees to his chest—doesn't hesitate to slip one finger in, then two, pushing in and out, stretching Mark's sopping hole. Mark wants to tell him to just get inside already, but Yuta is fucking him so well that he just writhes on Yuta's fingers, canting his hips so he can find just the right spot. 

Mark chokes as two fingers scissoring and stroking inside him turn into three. "Ready, ready, Yuta-hyung, please," he whines. Yuta curses, shoves down his underwear.

Mark's idly wondered before, but was never really sure what Yuta would look like down there, as a monster like him. He looks and there it is. Uncut, and beautiful, like a regular human cock. But still, he wonders—

Suddenly the blunt head of Yuta's cock nudges against his entrance, smearing the slick that's pooling and leaking out. Mark gasps, tries to wriggle and impale himself on Yuta's perfect cock, but Yuta easily stops him.

"Calm down, sweetheart. You're getting it." Then Yuta starts pushing in slowly, inching forward; the slow stretch is wonderful, utterly excruciating, but Mark just wants to be fucked.

It's sweet agony as Yuta finally bottoms out, his sac pressing against Mark. "Fuck, Markie, you're so fucking _tight."_ He pulls out almost completely, and Mark lets out a high-pitched keen at the emptiness, the loss. But Yuta slams in again, and again, punching a wounded cry out of Mark with each thrust.

Yuta hooks Mark's leg over his shoulder, and suddenly he's brushing up against Mark's prostate every single time. Mark shrieks a little with the pleasure of it—lets out the most pathetic whines and whimpers as he feels his pleasure building to ecstatic heights again. Mark could swear he feels Yuta's dick swelling inside him, even if it isn't real, isn't really a knot—but Mark likes Yuta _so much,_ will take anything Yuta has to give him.

 _"Alpha,"_ Mark whines, can't help himself, even if Yuta isn't a werewolf too. Yuta swears, fucking into him harder. Mark can't stop gasping and moaning; he feels himself winding tighter, tighter, until his pleasure explodes into white fireworks behind his eyelids. He feels his dick spitting come all over his stomach.

"My pretty Markie," Yuta murmurs, pounding harder and harder, his hips stuttering in their rhythm. "Look so pretty, coming all over yourself."

"Use me, Yuta, use me, want you to breed me," Mark babbles foolishly, blushing hard but meaning the words with all his heart. Even if it's impossible, he wants to be filled with Yuta, in every sense of the word.

Yuta groans, and Mark twitches and gasps helplessly as Yuta jerks and comes inside his still-spasming hole. It feels too soon that Yuta pulls out, so, so slowly, and Mark feels his eyes fill up with desperate tears, clenching down so that he can keep everything inside. He still _needs._

"More," Mark begs. His peripheral vision is a blur; all he can see is Yuta above him, and Mark's quickly losing his mind the longer Yuta isn't inside him. "Yuta-hyung, _more."_

"Fuck, baby, okay." Yuta sounds desperate, too.

Then Mark feels _them._ Slimy wetness slides over his thighs, spreading him wide open and on display. Mark keeps his eyes shut, whimpers and wriggles shamelessly as so much come and slick ooze out of his hole.

"Sorry, baby, is it okay? My tentacles, just until I get hard again, okay?" Yuta sounds... _embarrassed_ for some reason.

Mark can't see why, but he nods all the same. "I want everything, Yuta," he says, reaching up to touch Yuta's face.

Yuta gives him a brilliant smile, the same one that always takes Mark's breath away. "Get on all fours, sweetheart," Yuta says, kissing Mark's forehead and then drawing back.

Mark scrambles to obey, but his limbs aren't obeying him; he's so fucked out and feverish with heat. He whines plaintively.

Suddenly he feels tentacles wrapping around his wrists, his upper arms, everywhere. His eyes widen as he feels Yuta's tentacles position him just the way he wants, chest and cheek pressed to the bed, his ass high in the air with thighs spread wide apart. Mark's cock hangs between his legs, curving up and still hard, dripping.

Mark turns his head back as best he can; he sees mulberry-purple tentacles emerging from somewhere in the vicinity of Yuta's back, complete with suckers along their silvery undersides. They're beautiful, like Yuta.

"Hope you don't mind the extra help," Yuta says roughly.

Mark is on the verge of tears, actually, from how good this feels, how excited he is to be pinned down and made to _take._

Turns out he loves Yuta's tentacles at first sight; Mark parts his lips as one touches his mouth and lets it in, suckling at the tip curiously. It's spongy, and tastes of clean saltwater. Mark sucks harder to get more of Yuta's taste on his tongue, moaning and sending vibrations traveling through the soft, slimy appendage. Yuta gasps and moans low, thrusting deeper into Mark's mouth, tickling his throat. Mark almost gags but his mouth is opened too wide, lips stretched uncomfortably around the girth of Yuta's tentacle.

"Fuck, Mark," Yuta says, sounding choked-up himself. "You'll look so pretty, stretched on my tentacles." He pulls out the tentacle from Mark's mouth, letting him gasp for breath. Mark almost regrets the loss.

Two soft tentacle tips start probing at his sloppy entrance, stretching it further; Mark feels the burn of Yuta's stare as more fluid leaks out. His cock spits out a sorry little spurt of pre-come in excitement and Mark groans obscenely. "Please," Mark begs, needing to be filled again.

"So greedy for me, aren't you," Yuta teases, "I should make you wait."

But Mark needs him _now._

 _"Oppa,"_ Mark breathes out, feeling desire curl low in his belly like a flame. "Yuta-oppa, _please."_

Yuta freezes, Mark feels it, and for a terrifying second his blood runs cold and he thinks he did something wrong.

But then the tentacle starts pushing in, and Mark can't even moan as he's opened up again, deeper and wider than ever before. It feels like Yuta's trying to shove in the whole thing, and Mark starts to panic in little breathy gasps before Yuta pulls it out, torturously slow.

He _slams_ it back in.

"Yuta-oppa!" Mark screams, not caring who hears as Yuta fucks him hard and fast. Another tentacle wraps around his chest, suckers rhythmically pulsing and tightening around his nipples like wet mouths sucking and licking.

"That's it, baby," Yuta coos with such gentle fondness, at odds with the force of his thrusts. "You're being so good for me."

Mark feels the tentacle inside him retreat completely—then Yuta is sliding in again with his hard cock alongside the tentacle, and Mark feels so, so _full_. He's ruined for anyone else. There's no one who can fuck him this good, like Yuta can. Yuta's cock keeps grazing against his prostate, the tentacle massaging and circling around when he pulls out, squelching fluids leaking everywhere.

He feels sex-stupid, twitching from oversensitivity, but he doesn't want it to stop. Wants Yuta to keep fucking him like the good boy he is.

"Yuta, Yuta-oppa," he wails. It's perfect, it feels so perfect, and tears are coming to his eyes because of how perfect it is.

"Mark," Yuta groans in answer, reaching around to grip Mark's cock and give it a few tight, sloppy strokes before Mark is coming again, spasming on Yuta's cock and sobbing out his name. Wrung out and utterly ruined, Mark feels Yuta fill his gaping hole with come once more. Mark makes a soft, unhappy sound as Yuta pulls out, until he feels something else pushing in, plugging him up—it feels soft, malleable, and it stops the come from oozing out completely. Mark looks down: it's Yuta's tentacle, folded onto itself.

Like a knot, to keep Mark full.

Hot tears fill Mark's eyes as he whispers, "Thank you, thank you."

"Anything for you, sweetheart," Yuta murmurs, pulling Mark into his lap and kissing his damp brow. He dries Mark's tears with the blanket.

After some time, Yuta says gently, "Let's lie down, baby. I'll be right back to clean you up, okay?" Mark's caught in a sleepy, sex-drunk haze, but finds the capacity to nod, so Yuta carefully maneuvers him down to the bed. Mark barely notices Yuta leave, and in what seems like no time at all, Yuta returns with towels dampened with warm water and wipes down Mark and himself.

"Can we sleep in this room?" Yuta asks, gently carding a hand through Mark's hair.

Mark looks around blearily, trying to recall where they are. Now that he's well-fucked, his brain can focus on stuff that's not sex. "Yeah, guest room," he mumbles. Johnny is so rich, his house is a mansion. They'll probably have to camp out here for a while until Mark's heat subsides, but that's a topic of conversation for the morning.

Mark's arms and thighs are covered all over with sucker marks where Yuta's tentacles have gripped him just a little too hard. Like fingerprints. Mark presses one, ever so lightly, and smiles as he drifts off to sleep in Yuta's arms.

**Author's Note:**

> my first attempt at sort-of a/b/o and tentacles! i hope you enjoyed! :)
> 
> [twt](https://twitter.com/TheSunSparrow)


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